/**
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you under the Apache License, Version 2.0 (the
 * "License"); you may not use this file except in compliance
 * with the License.  You may obtain a copy of the License at
 *
 * http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package backtype.storm.scheduler.multitenant;

import java.util.Collection;
import java.util.HashSet;
import java.util.Iterator;
import java.util.Map;
import java.util.Set;

import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

import backtype.storm.scheduler.Cluster;
import backtype.storm.scheduler.TopologyDetails;

/**
 * All of the machines that currently have nothing assigned to them
 */
public class FreePool extends NodePool {
    private static final Logger LOG = LoggerFactory.getLogger(FreePool.class);
    private Set<Node> _nodes = new HashSet<>();
    private int _totalSlots = 0;

    @Override
    public void init(Cluster cluster, Map<String, Node> nodeIdToNode) {
        super.init(cluster, nodeIdToNode);
        for (Node n : nodeIdToNode.values()) {
            if (n.isTotallyFree() && n.isAlive()) {
                _nodes.add(n);
                _totalSlots += n.totalSlotsFree();
            }
        }
        LOG.debug("Found {} nodes with {} slots", _nodes.size(), _totalSlots);
    }

    @Override
    public void addTopology(TopologyDetails td) {
        throw new IllegalArgumentException("The free pool cannot run any topologies");
    }

    @Override
    public boolean canAdd(TopologyDetails td) {
        // The free pool never has anything running
        return false;
    }

    @Override
    public Collection<Node> takeNodes(int nodesNeeded) {
        HashSet<Node> ret = new HashSet<>();
        Iterator<Node> it = _nodes.iterator();
        while (it.hasNext() && nodesNeeded > ret.size()) {
            Node n = it.next();
            ret.add(n);
            _totalSlots -= n.totalSlotsFree();
            it.remove();
        }
        return ret;
    }

    @Override
    public int nodesAvailable() {
        return _nodes.size();
    }

    @Override
    public int slotsAvailable() {
        return _totalSlots;
    }

    @Override
    public Collection<Node> takeNodesBySlots(int slotsNeeded) {
        HashSet<Node> ret = new HashSet<>();
        Iterator<Node> it = _nodes.iterator();
        while (it.hasNext() && slotsNeeded > 0) {
            Node n = it.next();
            ret.add(n);
            _totalSlots -= n.totalSlotsFree();
            slotsNeeded -= n.totalSlotsFree();
            it.remove();
        }
        return ret;
    }

    @Override
    public NodeAndSlotCounts getNodeAndSlotCountIfSlotsWereTaken(int slotsNeeded) {
        int slotsFound = 0;
        int nodesFound = 0;
        Iterator<Node> it = _nodes.iterator();
        while (it.hasNext() && slotsNeeded > 0) {
            Node n = it.next();
            nodesFound++;
            int totalSlots = n.totalSlots();
            slotsFound += totalSlots;
            slotsNeeded -= totalSlots;
        }
        return new NodeAndSlotCounts(nodesFound, slotsFound);
    }

    @Override
    public void scheduleAsNeeded(NodePool... lesserPools) {
        // No topologies running so NOOP
    }

    @Override
    public String toString() {
        return "FreePool of " + _nodes.size() + " nodes with " + _totalSlots + " slots";
    }
}
